Redstone can be found in 54.0% of dungeon chests, in stacks of 1 to 4, and in 12.2% of stronghold altar chests, 25.2% of chest minecarts in abandoned mine shafts, 19.0% of stronghold storeroom chests, all in stacks of 4 to 9. Redstone dust can transmit power, which can be used to operate mechanism components (doors, pistons, redstone lamps, etc.). For different reasons, each signal can go up but not back down. Redstone dust can be "powered" by a number of methods: from an adjacent power component or a strongly-powered block from the output of a redstone repeater or redstone comparator from adjacent redstone dust. The powering dust can be a level higher or lower, but with restrictions: Redstone can be powered by redstone which is one level lower, or on an opaque block one level higher. A transparent block cannot pass power downward. The block "between" the two dust blocks must be air or transparent. A solid block there "cuts" the connection between the higher and lower dust.
The "power level" of redstone dust can vary from 0 to 15. Most power components power-up adjacent redstone dust to power level 15, but a few (daylight sensors, trapped chests, and weighted pressure plates) may create a lower power level. Redstone repeaters output power level 15 (when turned on), but redstone comparators may output a lower power level.